In Vivo Visualization of Calcium Transients during Fertilization and Early Development in C. elegans.

Calcium is an important signaling molecule during the oocyte-to-embryo transition (OET) and early embryogenesis. The hermaphroditic nematode Caenorhabditis elegans provides several unique advantages for the study of the OET as it is transparent and has an ordered gonad that produces one mature oocyte every ~23 min at 20 °C. We have modified the genetically encoded calcium indicator jGCaMP7s to fluorescently indicate the moment of fertilization within a living organism.

Visualization of the biphasic calcium wave during fertilization in Caenorhabditis elegans using a genetically encoded calcium indicator.

Fertilization is a critical step in development, yet internal fertilization events are notoriously difficult to visualize. Taking advantage of the calcium response that is a hallmark of sperm-egg fusion, we adapted the genetically encoded calcium indicator jGCaMP7s to visualize the moment of fertilization in Caenorhabditis elegans using fluorescence. We termed this tool the 'CaFE' reporter, for 'calcium during fertilization in C.